The goal of this study is to evaluate genetic and non-genetic risk factors for Alzheimer's disease and related disorders among patients from three distinct ethnic groups (black, Hispanic, and white) represented in the heterogeneous community of Washington Heights in the northern section of Manhattan. The second goal is to use this information in a series of investigations to establish the association between risk factors and Alzheimer's disease. The experimental design will be a case control study of subjects with dementia and subjects who do not exhibit difficulty with memory. A series of interviews will be conducted to collect information regarding environmental risk factors for dementia. In addition to the interviews, serum samples will be collected to study genetic mutations and plasma lipids.